For the cookie base:

1. Preheat oven at 350°F /180°C.
2. Have ready a 9 or 10-inch (24cm) springform cake pan with removable bottom. 
3. Grind cookies in the food processor until you have fine crumbs.
4. Add the melted butter, and mix until the mixture looks like wet sand.
5. Or add cookie crumbs to the bowl with the melted butter and mix with a spoon.
6. Put this mixture into the prepared pan and press firmly onto the bottom and up the sides of the pan. It will only cover about an inch up the sides.
7. Bake for 10 minutes. Let cool on a wire rack while making the filling.
8. Don't turn the oven off.

For the filling:

1. Preheat oven to 350º.
2. In a large bowl beat cream cheese on low speed until very smooth. You can use an electric mixer or wire whisk. If the cheese is at room temperature, mixing them by hand should not be a problem.
3. Gradually add both sugars and beat until well incorporated.
4. Add eggs, mixing until incorporated and scraping down the sides of the bowl.
5. Add melted chocolate and butter and mix. 
6. Add vanilla, baileys, and cream, stirring to incorporate well.
7. Pour the batter into the prepared pan and smooth the top.
8. Bake for 10 minutes at 350°F, turn the oven down to 280ºF and bake for another 40-45 minutes. (This can vary depending on your oven). At this point, the cheesecake should jiggle quite a lot. Don't be tempted to bake it longer. 
9. Turn the oven off and, leaving the door closed, let the cheesecake inside for 1 hour. It will keep on baking and firm up with the residual heat.
10. Take out of the oven and spread topping covering almost to the edges.
11. Cool to room temperature, wrap in plastic, and refrigerate for 8 to 12 hours. I recommend 1 day of refrigeration for the creamiest consistency.
12. Run a small knife around the edges to loosen up any bits that might be stuck, remove the cheesecake from the cake pan, transfer to the serving plate, and drizzle with chocolate ganache. 
13. Keep leftovers refrigerated, covered in plastic wrap.

For the topping:

1. In a bowl mix sour cream and baileys. 
2. You can add a few drops of vanilla extract if you want to. I normally don't.

For the chocolate drizzle:

1. Chop the chocolate and put it in a small bowl.
2. Heat cream in the microwave or stovetop.
3. Just when it's about to boil, remove and add to the chocolate. 
4. Whisk until chocolate is completely melted and the mixture is smooth. If you want it thinner in consistency add more cream or milk.
5. Drizzle over sour cream topping when the cheesecake is cold.